Recrystallization by rapid thermal annealing of implanted low-pressure chemical-vapor-deposited amorphous Si films

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Abstract
Amorphous Si films of 4000 Å were deposited using low-pressure chemical-vapor deposition and implanted with arsenic or boron at doses of 5×1013, 5×1014, and 5×1015 cm−2. These films were then rapid thermally annealed (RTA) using an Eaton Nova ROA-400 system at temperatures ranging from 900 to 1200 °C and dwell times ranging from 1 to 30 s. It was found that grain growth initiated very rapidly (less than 2 s at 1100 °C). Grain growth saturation (when grain size equals the film thickness) was reached in 5×1015 dose samples after a 1200 °C, 10-s RTA. The sheet resistance decreased with increasing RTA temperature and dwell time. Hall mobility increased with both RTA temperature and time. The temperature coefficient of resistance (TCR) was negative at low dose implants and became positive at higher dose implants. The lowest TCR was found in films implanted with medium dose. In general, 1200 °C/10-s RTA is an optimal condition for crystallization and annealing of the 5×1015 and 5×1014 cm−2 dose films while longer times are necessary for the 5×1013 cm−2 dose films.